Saudi Arabia's official press agency says one person was killed and three injured in a gunfight between "masked persons" and security forces in the country's eastern Qatif region.
SPA says the attackers opened fire on a police patrol late Thursday. The police fired back, injuring four people, one of whom died before reaching the hospital.
The oil-rich Qatif region, where most residents belong to the kingdom's Shiite minority, has seen frequent protests over the last year calling for political rights. The kingdom's Shiites make up 10 percent of the kingdom's 23 million people and complain of discrimination by the Sunni rulers.
Police shot dead one Shiite protester in the region last month, sparking further demonstrations.